1. Field of the Invention
The present invention relates to image processing apparatuses, image processing methods, programs, and recording media. In particular, the present invention relates to an image processing apparatus and an image processing method for processing face images, a program causing a computer to execute the method, and a recording medium having the program recorded thereon.
2. Description of the Related Art
Face image authentication techniques that allow authentication of whether or not face images match faces of pre-registered persons are known.
Authentication of whether or not face images match faces of pre-registered persons becomes difficult, when facial expressions of the target persons to be authenticated change. Accordingly, an authentication level is adjusted in some cases. For example, some techniques do not employ images of facial features that change as the facial expressions change in face images of the target persons to be authenticated for the authentication. Other techniques lower criteria (i.e., thresholds) used for the authentication while taking a risk of authenticating other persons as the subject persons by mistake into account so as to decrease an error of determining the subject persons as other persons.
A person identification device is known (see, for example, Japanese Unexamined Patent Application Publication No. 2004-110813). The person identification device includes a characteristic storage unit in which a face image of a person is pre-stored, a first input unit that receives face image data used for performing authentication of the person, arithmetic processing means that performs, after detecting characteristics of the face image of the person from the face image data, arithmetic processing on the characteristics, a second input unit that determines whether or not the arithmetic processing result matches with the face image of the person and receives facial expression data of the person on the basis of the matched data, arithmetic processing means that performs, after detecting characteristics of the facial expression from the facial expression data, arithmetic processing on the characteristics, and an authentication unit that determines whether or not a result of the arithmetic processing of the image data fed from the second input unit matches with the facial expression of the person and outputs matched data.